// https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp
#include <stdafx.h>
//-----------------------------------------------------------------------------
// MurmurHash3 was written by Austin Appleby, and is placed in the public
// domain. The author hereby disclaims copyright to this source code.

// Note - The x86 and x64 versions do _not_ produce the same results, as the
// algorithms are optimized for their respective platforms. You can still
// compile and run any of them on any platform, but your performance with the
// non-native version will be less than optimal.
#include "MurmurHash3.h"

//-----------------------------------------------------------------------------
// Platform-specific functions and macros
// Microsoft Visual Studio

#if defined(_MSC_VER)

#define FORCE_INLINE	__forceinline

#include <stdlib.h>

#define ROTL32(x,y)	_rotl(x,y)
#define ROTL64(x,y)	_rotl64(x,y)

#define BIG_CONSTANT(x) (x)

// Other compilers

#else	// defined(_MSC_VER)

#define	FORCE_INLINE inline __attribute__((always_inline))

inline uint32_t rotl32( uint32_t x, int8_t r )
{
	return ( x << r ) | ( x >> ( 32 - r ) );
}

inline uint64_t rotl64( uint64_t x, int8_t r )
{
	return ( x << r ) | ( x >> ( 64 - r ) );
}

#define	ROTL32(x,y)	rotl32(x,y)
#define ROTL64(x,y)	rotl64(x,y)

#define BIG_CONSTANT(x) (x##LLU)

#endif // !defined(_MSC_VER)

//-----------------------------------------------------------------------------
// Block read - if your platform needs to do endian-swapping or can only
// handle aligned reads, do the conversion here

FORCE_INLINE uint32_t getblock32( const uint32_t* p, int i )
{
	return p[ i ];
}

FORCE_INLINE uint64_t getblock64( const uint64_t* p, int i )
{
	return p[ i ];
}

//-----------------------------------------------------------------------------
// Finalization mix - force all bits of a hash block to avalanche

FORCE_INLINE uint32_t fmix32( uint32_t h )
{
	h ^= h >> 16;
	h *= 0x85ebca6b;
	h ^= h >> 13;
	h *= 0xc2b2ae35;
	h ^= h >> 16;

	return h;
}

//----------

FORCE_INLINE uint64_t fmix64( uint64_t k )
{
	k ^= k >> 33;
	k *= BIG_CONSTANT( 0xff51afd7ed558ccd );
	k ^= k >> 33;
	k *= BIG_CONSTANT( 0xc4ceb9fe1a85ec53 );
	k ^= k >> 33;

	return k;
}

//-----------------------------------------------------------------------------

void MurmurHash3_x86_32( const void* key, int len,
	uint32_t seed, void* out )
{
	const uint8_t* data = (const uint8_t*)key;
	const int nblocks = len / 4;

	uint32_t h1 = seed;

	const uint32_t c1 = 0xcc9e2d51;
	const uint32_t c2 = 0x1b873593;

	//----------
	// body

	const uint32_t* blocks = (const uint32_t*)( data + nblocks * 4 );

	for( int i = -nblocks; i; i++ )
	{
		uint32_t k1 = getblock32( blocks, i );

		k1 *= c1;
		k1 = ROTL32( k1, 15 );
		k1 *= c2;

		h1 ^= k1;
		h1 = ROTL32( h1, 13 );
		h1 = h1 * 5 + 0xe6546b64;
	}

	//----------
	// tail

	const uint8_t* tail = (const uint8_t*)( data + nblocks * 4 );

	uint32_t k1 = 0;

	switch( len & 3 )
	{
	case 3: k1 ^= tail[ 2 ] << 16;
	case 2: k1 ^= tail[ 1 ] << 8;
	case 1: k1 ^= tail[ 0 ];
		k1 *= c1; k1 = ROTL32( k1, 15 ); k1 *= c2; h1 ^= k1;
	};

	//----------
	// finalization

	h1 ^= len;

	h1 = fmix32( h1 );

	*(uint32_t*)out = h1;
}

//-----------------------------------------------------------------------------

void MurmurHash3_x86_128( const void* key, const int len,
	uint32_t seed, void* out )
{
	const uint8_t* data = (const uint8_t*)key;
	const int nblocks = len / 16;

	uint32_t h1 = seed;
	uint32_t h2 = seed;
	uint32_t h3 = seed;
	uint32_t h4 = seed;

	const uint32_t c1 = 0x239b961b;
	const uint32_t c2 = 0xab0e9789;
	const uint32_t c3 = 0x38b34ae5;
	const uint32_t c4 = 0xa1e38b93;

	//----------
	// body

	const uint32_t* blocks = (const uint32_t*)( data + nblocks * 16 );

	for( int i = -nblocks; i; i++ )
	{
		uint32_t k1 = getblock32( blocks, i * 4 + 0 );
		uint32_t k2 = getblock32( blocks, i * 4 + 1 );
		uint32_t k3 = getblock32( blocks, i * 4 + 2 );
		uint32_t k4 = getblock32( blocks, i * 4 + 3 );

		k1 *= c1; k1 = ROTL32( k1, 15 ); k1 *= c2; h1 ^= k1;

		h1 = ROTL32( h1, 19 ); h1 += h2; h1 = h1 * 5 + 0x561ccd1b;

		k2 *= c2; k2 = ROTL32( k2, 16 ); k2 *= c3; h2 ^= k2;

		h2 = ROTL32( h2, 17 ); h2 += h3; h2 = h2 * 5 + 0x0bcaa747;

		k3 *= c3; k3 = ROTL32( k3, 17 ); k3 *= c4; h3 ^= k3;

		h3 = ROTL32( h3, 15 ); h3 += h4; h3 = h3 * 5 + 0x96cd1c35;

		k4 *= c4; k4 = ROTL32( k4, 18 ); k4 *= c1; h4 ^= k4;

		h4 = ROTL32( h4, 13 ); h4 += h1; h4 = h4 * 5 + 0x32ac3b17;
	}

	//----------
	// tail

	const uint8_t* tail = (const uint8_t*)( data + nblocks * 16 );

	uint32_t k1 = 0;
	uint32_t k2 = 0;
	uint32_t k3 = 0;
	uint32_t k4 = 0;

	switch( len & 15 )
	{
	case 15: k4 ^= tail[ 14 ] << 16;
	case 14: k4 ^= tail[ 13 ] << 8;
	case 13: k4 ^= tail[ 12 ] << 0;
		k4 *= c4; k4 = ROTL32( k4, 18 ); k4 *= c1; h4 ^= k4;

	case 12: k3 ^= tail[ 11 ] << 24;
	case 11: k3 ^= tail[ 10 ] << 16;
	case 10: k3 ^= tail[ 9 ] << 8;
	case  9: k3 ^= tail[ 8 ] << 0;
		k3 *= c3; k3 = ROTL32( k3, 17 ); k3 *= c4; h3 ^= k3;

	case  8: k2 ^= tail[ 7 ] << 24;
	case  7: k2 ^= tail[ 6 ] << 16;
	case  6: k2 ^= tail[ 5 ] << 8;
	case  5: k2 ^= tail[ 4 ] << 0;
		k2 *= c2; k2 = ROTL32( k2, 16 ); k2 *= c3; h2 ^= k2;

	case  4: k1 ^= tail[ 3 ] << 24;
	case  3: k1 ^= tail[ 2 ] << 16;
	case  2: k1 ^= tail[ 1 ] << 8;
	case  1: k1 ^= tail[ 0 ] << 0;
		k1 *= c1; k1 = ROTL32( k1, 15 ); k1 *= c2; h1 ^= k1;
	};

	//----------
	// finalization

	h1 ^= len; h2 ^= len; h3 ^= len; h4 ^= len;

	h1 += h2; h1 += h3; h1 += h4;
	h2 += h1; h3 += h1; h4 += h1;

	h1 = fmix32( h1 );
	h2 = fmix32( h2 );
	h3 = fmix32( h3 );
	h4 = fmix32( h4 );

	h1 += h2; h1 += h3; h1 += h4;
	h2 += h1; h3 += h1; h4 += h1;

	( (uint32_t*)out )[ 0 ] = h1;
	( (uint32_t*)out )[ 1 ] = h2;
	( (uint32_t*)out )[ 2 ] = h3;
	( (uint32_t*)out )[ 3 ] = h4;
}

//-----------------------------------------------------------------------------

void MurmurHash3_x64_128( const void* key, const int len,
	const uint32_t seed, void* out )
{
	const uint8_t* data = (const uint8_t*)key;
	const int nblocks = len / 16;

	uint64_t h1 = seed;
	uint64_t h2 = seed;

	const uint64_t c1 = BIG_CONSTANT( 0x87c37b91114253d5 );
	const uint64_t c2 = BIG_CONSTANT( 0x4cf5ad432745937f );

	//----------
	// body

	const uint64_t* blocks = (const uint64_t*)( data );

	for( int i = 0; i < nblocks; i++ )
	{
		uint64_t k1 = getblock64( blocks, i * 2 + 0 );
		uint64_t k2 = getblock64( blocks, i * 2 + 1 );

		k1 *= c1; k1 = ROTL64( k1, 31 ); k1 *= c2; h1 ^= k1;

		h1 = ROTL64( h1, 27 ); h1 += h2; h1 = h1 * 5 + 0x52dce729;

		k2 *= c2; k2 = ROTL64( k2, 33 ); k2 *= c1; h2 ^= k2;

		h2 = ROTL64( h2, 31 ); h2 += h1; h2 = h2 * 5 + 0x38495ab5;
	}

	//----------
	// tail

	const uint8_t* tail = (const uint8_t*)( data + nblocks * 16 );

	uint64_t k1 = 0;
	uint64_t k2 = 0;

	switch( len & 15 )
	{
	case 15: k2 ^= ( (uint64_t)tail[ 14 ] ) << 48;
	case 14: k2 ^= ( (uint64_t)tail[ 13 ] ) << 40;
	case 13: k2 ^= ( (uint64_t)tail[ 12 ] ) << 32;
	case 12: k2 ^= ( (uint64_t)tail[ 11 ] ) << 24;
	case 11: k2 ^= ( (uint64_t)tail[ 10 ] ) << 16;
	case 10: k2 ^= ( (uint64_t)tail[ 9 ] ) << 8;
	case  9: k2 ^= ( (uint64_t)tail[ 8 ] ) << 0;
		k2 *= c2; k2 = ROTL64( k2, 33 ); k2 *= c1; h2 ^= k2;

	case  8: k1 ^= ( (uint64_t)tail[ 7 ] ) << 56;
	case  7: k1 ^= ( (uint64_t)tail[ 6 ] ) << 48;
	case  6: k1 ^= ( (uint64_t)tail[ 5 ] ) << 40;
	case  5: k1 ^= ( (uint64_t)tail[ 4 ] ) << 32;
	case  4: k1 ^= ( (uint64_t)tail[ 3 ] ) << 24;
	case  3: k1 ^= ( (uint64_t)tail[ 2 ] ) << 16;
	case  2: k1 ^= ( (uint64_t)tail[ 1 ] ) << 8;
	case  1: k1 ^= ( (uint64_t)tail[ 0 ] ) << 0;
		k1 *= c1; k1 = ROTL64( k1, 31 ); k1 *= c2; h1 ^= k1;
	};

	//----------
	// finalization

	h1 ^= len; h2 ^= len;

	h1 += h2;
	h2 += h1;

	h1 = fmix64( h1 );
	h2 = fmix64( h2 );

	h1 += h2;
	h2 += h1;

	( (uint64_t*)out )[ 0 ] = h1;
	( (uint64_t*)out )[ 1 ] = h2;
}

//-----------------------------------------------------------------------------
